Recently, eco-friendly vehicles have been developed using an electric motor as a driving source of a vehicle, and techniques of electric energy storage devices such as a battery as a power source of eco-friendly vehicles have also been rapidly developed. In addition, research and development has been conducted regarding internal/external vehicle devices and charging facilities for battery charging and expansion of a charging infrastructure, and the like.
As is known in the art, an eco-friendly vehicle such as an electric vehicle or a hybrid vehicle includes an electric motor as a vehicle power source, a motor control unit (MCU) (including an inverter) configured to drive an electric motor, a battery configured to supply power of an electric motor, and an in-vehicle charging device configured to charge a battery, and the like, and a charging port is also provided to connect a vehicle and an external charger.
The eco-friendly vehicle also includes a battery management system (BMS) configured to monitor a battery state and collect battery state information such as a voltage, a current, a temperature, a state of charge (SOC) of a battery pack, and provides the collected battery state information to other controllers within or extraneous to a vehicle. Thus, the battery state information may be used in operating a vehicle or executing battery charging. A battery of an eco-friendly vehicle may be slowly charged by connecting alternating current (AC) power (a slow charger) to a vehicle or rapidly charged by connecting direct current (DC) power (a rapid charger) to a vehicle. When a slow charger supplies AC power to a vehicle, the AC power is converted into DC power by an on-board charger (OBC) to charge a battery in the vehicle.
Meanwhile, a rapid charger is a charger that converts AC power into DC power and supplies the converted DC power to a vehicle. Since the rapid charger is directly connected to a battery of a vehicle and provides a high current, the battery may be completely charged within a short period of time. To charge a battery, a connector of a charger (the aforementioned slow charger or rapid charger) is connected to a charging port of a vehicle, and charge power of the charger may be supplied to the vehicle when the connector is connected. The connector includes a plurality of terminals such as a communication terminal for communication connection to a vehicle, a communication power supply terminal, a ground connection terminal, and the like, as well as a power supply terminal configured to supply charge power.
Additionally, a power relay assembly (PRA) configured to selectively supply power and cut off power supply is provided in a power line of a vehicle. The PRA includes a plurality of relays which are devices for interrupting a high voltage of a high voltage battery and which are fastened when a vehicle engine is turned on and disconnected when the vehicle engine is turned off. However, fusion that both contacts are fixed frequently occurs in a relay, and thus, a method for detecting such fusion and a method for more easily detecting fusion when a vehicle engine is turned on or off are required.